Method and apparatus for evaporating salt brine or the like



Dec. 9, 1958 w. H. FARNswoRTH 2,863,501

METHOD AND APPARATUS FOR EVAPORATING SALT BRINE 0R THE LIKE.

5 Sheets-Sheet 1 Filed Aug. 24, 1951 I N VEN TOR. wzaofi Dec. 9, 1958 w. H. FARNswoRTH 2,863,501

METHOD AND APPARATUS FOR EvAPoRATING SALT BRINE 0R THE: LIKE Filed Aug. 24, 1951 5 Sheets-Shea?l 2 IN VEN TOR.

Dec. 9, 1958 w. H. FARNSWORTH 2,853,501

METHOD AND APPARATUS FOR EVAPORATING SALT BRINE 0R THE: LIKE l Filed Aug. 24. 1951 5 Sheets-Sheet 5 Dec. 9, 1958 w. H. FARNswoRTH 2,863,501

METHOD AND APPARATUS FOR EVAPORATING SALT BRINE OR THE LIKE Filed Aug. 24. 1951 5 Sheets-Shee. 4

@fils Dec. 9, 1958 w. H. FARNswoR-rH 2,863,501

METHOD AND APPARATUS FOR EVAPORATING SALT BRINE 0R THE LIKE Filed Aug. 24. 1951 5 Sheets-Sheet 5 l N V EN TOR. fzswof H07 BRI/Vl 7'0 LEG PIPE i Wl COOL CONN/V567? BY 7M/.QQ ML),

United States Patent O METHOD AND APPARATUS FOR EVAPORATING SALi` BRINE R THE LIKE William H. Farnsworth, Manistee, Mich.

Application August 24, 1951, Serial No. 243,565

26 Claims. (Cl. 159--24) My invention relates to improvements in the method of, and apparatus for separating or producing solids or crystalline material from a solution thereof. More particularly, my invention relates to improved means for utilizing the principle of vapor compression in my improved method for producing solids or crystalline material from a solution thereof.

Prior to my invention, the research of others has been directed towards the production of potable water from such sources as sea water, or for the production of high purity water for laboratory or hospital use. However, the problems involved, and the various objects accomplished in applying the principles of vapor compression to the production of solid phases from a solution thereof, are quite different, and much more involved than a system solely for the production of water. In order to accomplish the various objects ofmy invention, the principle of vapor compression will be applied in such a manner as to make possible the assembly of the necessary number of standard pieces of equipment so as to develop a package or complete unit plant. This is highly desirable in order that a package plant, particularly, as an example, for producing salt, is compact, easily erected, and easily moved so that it may be erected in remote areas far from the usual sources of power. It is also highly desirable that the assembled unit is capable of being operated completely on the basis of the fuel or energy used for power for operating the prime movers for actuating the various units forming the package plant. This process is accomplished by the assembly of certain units of standard equipment, such as a diesel engine for motive power, or otherrforms of internal combustion engines, compressors, or heat pumps for applying vapor compression to the solution to be evaporated, which, when erected and arranged, as will be more particularly described, forms a producing plant involving less capital investment and greater operating economies than any of the prior art evaporating plants now in use.

It is therefore a principal objective of my invention to provide a novel method of, and apparatus for applying vapor compression to the production of solid phases from solution which require less capital investment, and provide greater operating economies than heretofore known, and to produce a `package plant such as for producing refined salt which is economical to operate in remote areas.

Since the package plant of my invention is adapted for being operated in remote areas, and also where the supply of fresh water is limited, another object of my invention is to provide a method of, and apparatus for the recrystallization of salt which will require a very minimum of fresh makeup water.

Another object of my invention is to provide a method which will separate solids or crystalline materials from a solution or from naturally occurring brines more economically than is possible with available processes.

Another object of the invention is to provide a simple system for the recrystallization of salts which requires Patented Dec. EL

not only a very minimum of water, but operates where it is desirable to recrystallize to improve purity or cleanliness of the salt or resultant product, and fresh water is scarce or not available, such as in remote, inaccessible, foreign areas. l

Another object of the invention is to provide a method of utilizing the waste heat recovered from the prime mover or driving engine used in the evaporative process by combining it with the heat recovered by the compression cycle of the compressor operatively connected to the prime mover, and which is used to compress the vapors of the solution to be evaporated; particularly as this heat is made available to the System, it assures a surplus of heat to the system to maintain the recompression cycle.

Still another object of the invention is to incorporate in this improved evaporative process or system the step of producing the small amount of make-up water required by the system from any saline or contaminated water available at the selected site.

An additional object of the invention is to provide an improved evaporative system that possesses far greater heat economy than multiple effect evaporators usually used in evaporative processes.

Another object of the invention is to provide an improved process for producing solids or crystalline material from solution, which may perform all the necessary steps without the need of steam boilers or condensers.

Another object of the invention is to provide an improved method of utilizing waste heat recovered from the driving engine for the compressor in the process of producing solids by combining with it the surplus heat recovered from the compression cycle of the vaporized solution.

Still another object of the invention is to provide an economical plant and pro-cess for the production of `sodium chloride or common salt.

Still another object of the invention is to provide a source of electrical power where necessary in the operation of the necessaryauxiliaries and lights, preferably driven from the same prime mover utilized in driving the compressor for compressing the vapors of the solution in the compression cycle of the process.

The features of this invention relate to a novel method and means for utilizing the available power and heat losses of an internal combustion engine in conjunction with vapor compression of the hot vapors'of the solution being evaporated so as to improve the operation and efficiency of the vapor compression system of the evaporative process of this invention. In accordance with the present invention, a source of energy in the form of fuel supplied to the internal combustion engine supplies energy in the form of mechanical energy generated by the engine, such as a diesel engine, for compressing the vapors of the solution being evaporated, and this energy .is supplemented by the heat that is derived from the cooling water circulating through the engine for cooling the engine and the exhaust gases therefrom, which normally would be lost without useful effect. Certain of the features of this invention relate to the manner of absorbing this heat from the engine into the system without interfering with the proper balancing of the heat cycle thereof.`

Other features of this invention relate to means for maintaining the internal combustion engine at the proper operating temperature by circulating the engine-cooling water through the engine and a waste-heat boiler for con serving the waste heat of the exhaust gases, and through the Calandria of the evaporator in which the solution from which the solids are separated are heated.

Another feature of the invention is to provide for an auxiliary evaporator for providing water to the salt dissolver.

Another feature of the invention is to provide a brine pump-back tank and boil-out water tank for storage purposes, the pump-back tank containing the brine from the evaporator during the boil-out period, and the boil-out water-tank supplying the water for this operation, which consists of removing the solids which have accumulated within the evaporator by boiling with fresh water.

Still another feature of the invention is to provide a simple form of compressor driven by the engine forY compressing the hot vapors from the evaporator of the system. In this invention, it is preferred to drive the cornpressor using an internal combustion engine in order to use the waste heat of the engine, although it is within the scope of the invention to drive the compressor from a suitable source of electric power which may have been supplied from an internal combustion engine directly connected to a generator, the internal combustion engine still supplying the necessary heat for vaporizing the solution to be evaporated. When an internal combustion er1- gine, such as a diesel engine, is utilized in this system to actuate a rotary compressor, the various embodiments of the invention may be utilized in an advantageous manner to bring about a useful relationship between the energy supplied to the compressor by the internal combustion engine and the waste heat incidental to the operation of the diesel engine, and in addition, the heat losses which may occur during the evaporative processes. These improvements relate both to the method and apparatus utilized in carrying out the evaporative process.

The portion of the heat which is developed in the cornbustion process of the diesel engine utilized must be removed to prevent overheating of the engine, and the cooling water which isrcirculated through the engine and through a waste heat boiler operatively connected to the exhaust of the engine to fully utilize the waste heat from the engine will be referred to as the engine-cooling water which is heated as described above, and then circulated through the Calandria of the evaporator of the process. If needed, before the cooling water enters the evaporator, resistance may be added in the piping to prevent flashing,

Vand also, the ow thereof to the heating element of the Calandria may be divided. Normally the heat is wasted to the atmosphere, and the usual cooling fan necessary to cool the engine causes a substantial loss of power. It is thus an additional feature of this invention that the waste heat from the diesel engine may be put to useful service in carrying out the evaporative process of this invention, and thus there will be effected heat savings which otherwise would have to be supplied from another source.

Other features of the invention relate to the cycle of this invention wherein excess heat from the system is introduced into the evaporative system without disrupting the heat cycle. Y

This invention also provides for economies in operation, and also permits of such simplification and compactness of the apparatus that a minimum of space is necessary for the erection of the entire system, including the evaporator, the engine compressor, and the Various tanks for circulating the brine or slurry of a solid solution from which the solid or salt is to be separated.

Many other objects and advantages of the construction herein shown and described will be obvious to those skilled in the art from the disclosure herein given.

To this end, my invention consists in the novel construction, arrangement, and combination of parts herein shown and described, and more particularly pointed out in the claims.

In the drawings, wherein like reference characters indicate like or corresponding parts:

Fig. 1 illustrates a schematic layout of equipment and piping for a one-ton-per-hour unit salt plant;v

Fig. 1A illustrates an auxiliary water distillation unit using a heat exchanger for use in the salt plant of l;

Fig. 2 is a view in elevation illustrating the arrangement of a cast iron evaporator, and other auxiliary equipment of the salt plant of this invention illustrated schematically in Fig. 1;

Fig. 3 is a plan view of the evaporator, engine, and centrifugal filter of the apparatus of Fig. 2;

Fig. 4 is a view in elevation of the plant of Fig. 1, illustrating the condensate receiver mounted on the evaporator, and has the calandria of the evaporator broken away to show the heat exchange portion of the Calandria and the circulator for the'brine;

Fig. 5 is a plan view illustrating the tank location of the boil-out water tank, pump-back tank, and condensate receiver located with respect to the evaporator and salt dissolver and brine well thereof of the salt plant shown schematically in Fig. 1;

Fig. 6 is a side view in elevation, taken along line 6 6 of Fig. 5, showing the boil-out water tank, pumpback tank, and the filling pump;

Fig. 7 is a side View in elevation of a modified one-ton unit salt plant evaporator fabricated from steel members or from members of other metals;

Fig. 8 is an enlarged view of the modified salt plant, taken along line 8-8 of Fig. 5, illustrating the condensate receiver, fresh water heater, brine heater, exhaust heat boiler, and piping to the evaporator; and

Fig. 9 is an enlarged plan view of the fresh water heater, brine heater, and condensate receiver and piping therefor of Fig. 8.

Referring to Fig. 1, there will be described the schematic layout for a unit salt plant of substantially one-tonper-hour capacity of this invention in which the principles and problems involved, and the results accomplished in applying vapor compression to the production of solid phases from a solution of the solid to be separated, and in this particular instance, salt from a brine solution,'is

quite different and much more involved than in a simple lsystem for the production of water only. In accomplish- 'ing the various objects of the invention, the principle of applying vapor compression has been utilized in such manner as to make possible the assembly of the necessary number of standard pieces of equipment so as to develop a package or a complete unit plant, such as illustrated schematically in Fig. 1, and structurally in Figs. 2, 3, 4, 5, and 6. This plant therefore may be shipped to remote locations where there is no source of available power, and where there is very little water to provide the solution. The complete unit plant of this invention is therefore capable of being operated completely o-n the basis o-f the fuel or energy used for operating the power for driving the compressor for compressing the vapor and, if necessary, excess power may be supplied even for operating a generator for providing the necessary lighting and auxiliary power for operating the auxiliary pumps, and the like, that are necessary, as well as other equipment such as the filter, driers, and conveyors completing the plant. Therefore, the novel process of this invention is accomplished by the assembly of carefully chosen units of standard equipment which, when brought together in the novel system of this invention, create a salt producing plant, for example, for much less capital investment, and much greater operating economies than any of the standard evaporating plants now in use. Although this invention will be described particularly with respect to a plant and process for the production of sodium chloride, or common salt, it may be altered within the scope of the invention to t the requirements of any evaporative process where it is desired to separate a solid from a solution which may be readily vaporized.

Referring to Fig. l, the preferred arrangement of the equipment and piping for a one-ton-per-hour unit salt plant will now be described. In order to explain the operation of this plant more clearly, and the relationship of the various pieces of equipment, the schematic layout of Fig. l shows the interrelationship of each piece of equipment. In the Figs. 2, 3, 4, and 5 is shown a preferred arrangement of the apparatus described with ref- "erence tothe Yschematic layout of Fig. 1. Like reference characters will indicate the same or similar parts. Starting with a salt dissolver 10, where rock salt or solar salt is dissolved in condensate produced by the evaporative process, the feed brine, at a temperature of substantially 85 F., is picked up by a brine pump 11 and passed through a 11A conduit 12 at the rate of substantially twenty-two gallons per minute, through a heat exchanger 13 having a heat exchange surface of 100 square feet, wherein the temperature is raised from 85 F. to 136 F., and then circulated through a 11/2" hot brine conduit 14 to a leg pipe 15 which is connected to an evaporator body 16. This brine, in passing through the internal Calandria 17, is brought to boiling temperature of substantially 248 F., and the vapor is removed from the evaporator 16 in a 16" conduit or vapor line 18 by a compressor 19, and discharged through a 12 conduit 20 to the Calandria 17. The Calandria and evaporator are similar to a crystal building pan, as disclosed and claimed in the patents to T. Ray et al., No. 1,860,118, granted May 24, 1932; and to J. R. Ray et al., No. 1,785,530, granted December 16, 1930, and 1,428,557 of Sept. 12, 1922; and has been modified thereover so that it may be arranged in the completed unit plant for assembly, as shown in Figs. 2, 3, and 4. The compressor 19 is driven by an internal combustion engine 21 of a diesel type, see Fig. 2. The compressor may be of the positive blower type having a compression ratio of substantially two to one, and the engine for a one-ton-per-hour salt plant may be substantially 240 horsepower engine having a 39 gallon capacity cooling system. The compressor 19, as the vapor is compressed, adds the heat of compression. The compressor may be a Standardaire or Roots-type blower having intermeshing, impeller fans.

It is also within the scope of my invention to carry out my process without the utilization of the 100 sq. ft. heat exchanger 13. When operating the apparatus in this manner, suitable valves (not shown) in Fig. l may bypass the hot condensate of 235 F. in the line 33 so that it does not pass through this heat exchanger, or the heat exchanger 13 may be omitted, optionally, entirely from the process. With either the heat exchanger in the system and by-passed, or without it, the process may then be operated so that the feed brine previously reaching a temperature of 136 F. after entering the heat exchanger 13 at 85 F. now becomes substantially 200 F. and is fed directly to the leg pipe 15 as previously done. The hot condensate, reaching a temperature of 235 F. as it leaves the sq. ft. heat exchanger 32 through the pipe 33, instead of becoming cooled off as before as it was r circulated through the heat exchanger 13, now is directly discharged to the salt dissolver 10 as the iloat 29 in the Acondensate-receiving tank 23 is operated, and increases the temperature of the solution within the salt dissolver. This increased temperature of the condensate through the pipe 34 heats the salt solution in the salt dissolver to a temperature of `substantially 200 F. rather than as previously to substantially 85 F.

The vapors admitted to the Calandria 17 are condensed therein, and passed through conduit 22 to a 1000 gallon condensate receiving tank 23, from which the llow is divided. The necessary Water to remove the excess and waste heat from the engine 21 Hows out of the condensate receiving tank 23, through a conduit 24 to an engine pump 25, pumping at the rate of 130 to 150 gallons per minute, through water jackets of engine 21, and out through a conduit 26. The engine cooling water is discharged through a waste heat boiler 27 in heat transfer relationship with the exhaust of the engine, and is returned to the Calandria 17 through a conduit 28. The engine cooling water for the particular installation is pumped at the rate of approximately 120 gallons per minute by the pump 25, which has a rated capacity of from 130 to 150 gallons per minute. The cooling water for the engine is continuously recycled at a uniform rate.

The portion of the condensate from the Calandria 17 resulting from the condensation of the produced vapors also passes through the conduit 22 to the condensate receiver 23, and this water tends to accumulate in the tank 23, which, in the particular instance, has a capacity of substantially 1000 gallons. As the water tends to accumulate in the tank 23, a oat 29 is raised which opens a valve 30. When the valve 30 is opened, condensate collected in this tank may then flow by a conduit 31, and discharges through a fresh Water heat exchanger 32 having ten square feet of heating surface, and through a `conduit 33 at a temperature of 235 F., to the brine heater 13. The hot condensate flowing through the line 22 is substantially within the range of 248 F. and, as indicated, may be Iby-passed about the fresh Water heater 32, or directed through it to heat the fresh Water, the fresh water being at a temperature of substantially F. This will be particularly described with reference to the operation.

This hot condensate, in passing through the heat exchangers 13 and 32, gives up its excess heat to the fresh Water being accumulated for boil-out Water at a temperature of substantially 210 F., and to the feed brine to the evaporator 16. After being cooled, it passes through the 1%" conduit 34 at a temperature of substantially 112 F. and a rate of flow of twelve gallons per minute, and then through the valve 30 actuated by the float 29, and back to the salt dissolver 10. The salt dissolver for the particular one-ton-perhour unit salt plant being particularly described is adjusted to dissolve at the rate of twenty-two gallons per hour.

The salt produced in the evaporator 16 accumulates in the salt leg 15, where it is picked up by a slurry pump 35, and is pumped through a 11/2 conduit 36 to a centrifugal lter 37. The filtrate from this unit is then pumped back thro-ugh a 11/4" conduit .te at tue rate of 5,000 pounds per hour or 8.35 gallons per minute by the suction of a brine pump 11 connected to a brine Well 10a of the salt dissolver and to the conduit 38. The salt is discharged from the centrifugal litter 37 to an elevator 39, and from there to a drier 40, after which it is discharged to an elevator 41. The elevator 41 discharges Vthe dry salt to a discharge bin 42, after which it may be bagged, or packaged.

Heat is applied to the drier 40 by an oil-tired, indirect form an operation called boil-out to remove the lumps and scale which form in the evaporative unit. In order to accomplish this, the compressor 19 is .shut down, and the brine in the evaporator body 16 is then permitted to pass out through a 4 conduit 46 when valve 47 is opened, to a pump-back tank 48, where the brine and solid suspension are held until the boil-out operation is completed. The pump-back tank is a temporary storage tank having a capacity for this particular unit of approximately 1750 gallons. Fresh water, at a temperature of approximately 55 F. is admitted to the heater 32 through a conduit 49 at such a. rate as to supply the necessary amount of Water required during the forty-eight or seventy-two hour operating period. The hot water from the fresh water heater 32 is heated to a temperature of substantially 210 F. by the hot condensate having a temperature of substantially 248 F.

asas-soi After the water is heated, the water passes out through a 1% conduit 50 to a boil-out water storage tank 51. This tank, for this particular operation, has a storage capacity for the boil-out water of approximately 3500 gallons.

When this water is required for this operation, it is sucked through a four inch pipe line 52, when valve S3 is opened, by a tilling pump 54, through a 4 connecting pipe 55 to a portion of the pipe 46, to which it is connected, where it is discharged into the leg pipe 15 of the evaporator. In performing this operation, the valve 47 is closed before the pump 54 is started. In performing the boil-out operation, the compressor 19 is operated so as to remove the vapors from the evaporator body 16, making them available in the Calandria 17 to supply heat for the boil-out operation. When the boil-out operation is completed, a Vvalve 56 is opened and valve 53 closed, and the boil-out water passes through a 4 boil-out water pipe line 57, where it is discharged into `the salt dissolver 10. In locations where fresh water is not readily available, the boil-out water should be suiiicient to make up for any losses in the condensate system. After the boileout water has been removed from the evaporator body 16, the valve 56 is Closed, and valve 65 is opened. The brine and slurry held in the pump-back tank 48 is then discharged through the pump 54 through the connecting pipe 55 and piping 46, to the leg pipe 15, so that when this brine has been returned to the evaporator body 16, it should be at approximately the same level as when the system was shut down for the boil-out period. The filling pump 54 has a capacity of from 120 to 152 gallons per minute. There is a by-pass around the heat exchanger 32 which is controlled by a valve 58, which is actuated by a thermostatic element 59 through control tube 58 located in the `boil-out water tank 51, the function of which is to maintain the boil-out water at a constant temperature of substantially 210 F. There is a by-pass around the heat exchanger or brine heater 13 in which a valve 60 is inserted, and is actuated by a thermostatic control element 61 through control tube 60', inserted in the vapor space of the evaporator 16, the function of which is to maintain the temperature of the feed brine through heat exchanger 13 at the temperature of substantially 136 F.

The feed brine enters the brine heater from the and is heated by the hot condensate having a temperature of approximately 235 F. after it leaves the fresh water heater 32. The hot brine, as it leaves the brine heater, has a temperature of approximately 136 F.

In starting up Cold, a by-pass valve 62 is opened so that when the engine 21 is started, the compressor 19 is brought to full load by recycling the air contained in the Calandria 17. The heat added by compression, plus the waste heat recovered from the engine 21 and the use of available electric energy, or other source of heat through vheat exchangers (not shown) within the evaporator 16 is suiiicient to bring the evaporator 16 up to operating temperature in about two hours time. The operating temperature of the Calandria is approximately 248 F. New starts after boil-out are immediate because all solutions are maintained at their operating temperature. An air vent 63 is provided on the condensate receiving tank 23 to remove the non-condensing gases from the system. An air vent 17a, schematically shown in Fig. l, may be Yused in relationship to the calandria for venting nonwater where fresh make-up water is not available to meet the requirements, a small auxiliary evaporator 66 may be added to the system. This evaporator may distill saline or contaminated water to provide useful make-up water 'for the system. Heat for this auxiliary unit is available from the excess heat of the high temperature cooling system of the engine, the heat content of which has been increased by compressing the vapor from the evaporator 16.

Vapor from the discharge side of the heat pump or compressor 19 is discharged through a conduit 67 to provide suliicient heat to produce the required amount of condensate water in the evaporator 66. Vapors from. this evaporation are returned to the suction side of thef heat pump through a 11/2" conduit 68 connected to the conduit 18. In order to prevent additional loss of heat: from the system, a heat exchanger 69, as shownin Fig.. 1A, may be provided. If this is not desired, the contaminated water to be purified may be discharged into the auxiliary evaporators 66 through a pipe line 72, andi the pure make-up water, after it has been freed from impurities, or condensate is discharged through the pipingt 71 directly to the salt dissolver 10. The raw water used for condensing the vapors received through vapor pipe: 67 is discharged through the piping 70. This provides' a very simple system for producing a pure make-up water' where only contaminated water is available.

The system is also capable of being operated without: the auxiliary evaporator for make-up water when there` is available a suitable supply of fresh make-up water.. Such being the case, the auxiliary evaporator 66 wouldl be detached from the system by disconnecting the pipe 68 from the piping 18, and the pipe 67 from the discharge side of the Compressor 19.

In the preferred system shown, Fig. 1A, in which the heat exchanger 69 is added to prevent loss of heat, the contaminated, raw water is passed through the heat ex` changer 69 through conduits 72 and 72a, picking up heat from two sources: first, from the pure condensate as it leaves the auxiliary evaporator 66 through conduits 71 and 71a; and second, through the continuous blow-down necessary to keep concentration of brine or contaminated water in the evaporator 66 at a low density, through conduits 70 and 70a. This heat exchanger obviously is provided with separate passes to accommodate the two sources of heat, but has been shown schematically for the purpose of this disclosure. The pure condensate discharged through piping 71a may then be returned to the salt dissolver 10.

Also, in the operation of the system it may be necessary to pro-vide a fogging nozzle 64. The fogging nozzle 64 connected in a condensate line 22a is inserted into vapor line 18 at suction of compressor 19 to spray water into the hot vapors from the evaporator just ahead of the compressor or to spray condensate into compressor to maintain a wet rotor to prevent accumulation of salt scale within the compressor, particularly to prevent salt scale forming on the rotor, and to remove the super-heat caused by compression. If necessary, as the engine cooling water is discharged into the Calandria through the piping 28, it may be desirable to add a resistance to prevent flashing, and also to divide the flow. An orifice, or the like, may be added to supply the necessary resistance.

Referring to Figs. 2, 3, and 4, there is illustrated a preferred embodiment of my invention showing the structural arrangement of certain `of the apparatus described previously with reference to the schematic layout of the system of Fig. 1. The evaporator 16 is preferably fabricated from several conical-shaped sections provided with lianges for securing the sections together, and is supported above the Calandria 17, which is shaped as shown in the broken-away sections of Figs. 2 and 4, illustrating a circulator 75 located contiguous tothe curved bottom portion of the Calandria, which is connected to discharge the salt crystals into the leg pipe 15. The circulator 75 circulates the brine solution upwardly through pipes 76, and back down through a central opening 77. The pipes 76 are in heat exchange relationship, with the compressed vapors discharged into the Calandria 17 about the pipes 76 from the heat pump or compressor 19, andthrough a 12 pipe 20 operatively connected to the steam belt of the Calandria. The form of the Calandria is such as disclosed and claimed in the abovementioned applications. In the evaporators disclosed in the aforementioned applications, the drive for the circulators is extended down through the entire evaporator construction. As the shaft of the circulator 75 extends through the bottom of the evaporator, the drive and the mechanism for actuating this circulator 75 is simplified. The circulator is operated through a suitable gear reduction 78 driven from a directly connected electric motor 79, the power for which may be delivered by auxiliary generators provided in the plant, or may be furnished by a generator (not shown) directly connected to the diesel engine or internal combustion engine which also serves to drive the compressor 19. The evaporator and connected calandria 17 are supported upon vertical columns 80, which are suitably braced as shown in Figs. 2 and 4, and provide a platform for the gear reduction and motor drive for driving the circulator 75, and in addition, provide a support for ladders S1 and platforms 82 arranged at convenient locations for the inspection of the apparatus during operation.

The support or platform for the drive for the circulator is also extended, and provides, in addition, a support for the condensate receiving tank 23. The upper end of the evaporator 16 is connected to a vapor dome construction 83 and a separator 84 to remove any moisture from the hot vapors withdrawn downwardly through the sixteen inch suction line 18 to the vapor pump 19, where they are suitably compressed at substantially a 2-l ratio, and returned through the twelve inch discharge Vline 20 to the steam belt of the Calandria 17. When desired, a fogging nozzle construction 64, which is connected to condensate water line 22a, and inserted in vapor line 18 at suction side of compressor, discharges a spray of water into the vapors in such quantity as to remove the super heat caused by compression and to maintain wet rotors so that salt is n'ot formed on the interior moving parts of the compressor.

The engine 21 directly connected to the heat pump or compressor 19 is arranged contiguous to the base of the apparatus to provide, as shown, pipe lines as short as possible for the connecting of the suction line 18 to the vapor pump, and the discharge line 20 thereto. The by-pass valve 62 is shown connecting the vapor line 18 to the calandria 17 in order to heat up the Calandria during the starting operation when the valve 62 is opened, thus bypassing the vapor space.

Also arranged to one side of the base of the apparatus, as shown in Figs. 2 and 3, is the centrifugal filter 37 connected to deliver the refined salt to the elevator 39. The centrifugal lter is driven through a motor drive 85, shown in Fig. 3.

The slurry pump 35 is connected to the leg pipe 15, an'd discharges the salt slurry from the leg pipe through a one and one-half inch pipe line 36 to the centrifugal filter 37. A suitable valve 36' may be placed between the slurry pump 35 and the leg pipe 15. A 4" conduit 46 is also shown connected to the leg pipe for connecting the pump-back tank` thereto. The hot brine pipe 14, suitably valved by the lloat-controlledvalve 45 operated from the oat 44, is connected to the bottom of the leg pipe i5.

In order to determine the level of the `brine within the evaporator, a suitable level column and sight glass 86 is connected to the lower section of the evaporator 16, as shown in Fig. 4. The level column and sight glass may be suitably inspected by using the ladders S1 and plat forms 82, shown in Fig. 4.

From the above disclosure of the particular arrangement of the apparatus, there has been provided a very compact plant arrangement which will fit into a minimum of space, thus reducing the capital outlay for buildings, and has been so constructed that the entire apparatus has lanV over-all height of substantially fo-rty-three feet for simplifying the erection of 'the plant in out-of-theway- 10 places, and only rigging that is locally available is needed, as the sections forming the evaporator and the Calandria have all been constructed of minimum size for ease in handling and erecting.

Referring to Figs. 5, 6, 8, and 9, there is shown applicants arrangement of the tank locations and piping for the salt plant of this particular embodiment. Referring particularly to Figs. 5 and 6, the boil-out water tank 51 and pump-back tank 48 are shown connected to the common conduit 46, and having interposed therein the respective valves 47 and 56. The filling pump 54 is shown connected to the line 46, an'd has the valves 53 and 65 suitably arranged. The 1%. hot water line 50 is shown connected between the boil-out Water tank 51 and the fresh water heater 32. The 11/2" hot brine conduit 14 is shown connected to the leg pipe 15 and the 'brine heater 13. The fresh water heat exchanger 32 has ten square feet of heat exchange surface, while the brine heater 13 has square feet of heat surface.

As shown in Figs. 5 and 8, it is preferred to arrange the fresh water heater 32 and the brine heater 13, as shown, above the condensate receiver 23 to simplify the piping arrangement. The motor driven brine pump 11 is shown in the brine Well 10a located contiguous to the salt dissolver 1t), which may be large tanks constructed of masonry and set in the ground to provide gravity flow for the return of the boilout Water and condensate to the salt dissolver.

Referring to Figs. 5 and 8, there is shown the piping arrangement for the exhaust heat boiler 27 connected to the exhaust 27 of the engine 21. The 3 pipes 26 and 28 discharge the engine cooling water from the passages within the engine through the exhaust heat boiler 27 at the rate of approximately gallons per minute. Referring to Fig. 5, a water circulating pump 25 discharges condensate from the condensate receiving tank 23 through 3" piping 24 for circulating approximately 130 to 150 gallons of cooling water per minute through the internal combustion en'gine. As illustrated in Figs. 5 through 9, it is obvious that there has been shown a simple arrangement for the tank locations and piping to connect, with a minimum amount of pipe, the various auxiliaries needed in the operation of the preferred form of salt plant of this invention. The arrangements shown in Figs. 5 through 9 are arranged in accordance with the schematic diagram of Fig. 1, and are particularly shown in connection with a modified form of salt plant shown in Fig. 7, which is constructed entirely of steel rather than from cast iron, as is shown in' the embodiment of Figs. 2 through 4 previously described.

Referring to Fig. 7, the steel construction will be described, and like or primed reference characters will denote the same or similar parts. The evaporator 16 is constructed as a single steel cylinder rather than from sections as is the cast iron evaporator of Fig. 4. For the sake of clearness, the embodiment of Fig. 7 has been arranged somewhat differently than that of Fig. 4 to provide for ease in' construction, and is similarly supported on structural steel columns Sii inclined to the axis of the evaporator, and welded to the Calandria portion 17. The construction of the tubing 76 and central circulatory passage 77 is the same as in the previous embodiment. A circulator 75 is mounted within a conical portion rather than the arcuate portion shown' in Fig. 4, to Which is connected a leg pipe 15. The circulator 75 is driven through a suitable motor-driven, gear reduction apparatus 73 and 79, and the engine 21 and rotary type heat pump 19 is arranged as shown for discharging the compressed gases upwardly through a conduit 20 connected to the steam belt of the Calandria 17. Similarly, a level column and sight glass 86 is mounted on the outer periphery of the evaporator 16', as shown. Peep lights 87 are arranged about the periphery of the evaporator 16', and manholes 88 are also arranged for the inspection of the evaporator 16 and Calandria 17. Although manholes 11 and peep lights have not been illustrated in connection with the embodiment of Figs. 2, 3, and 4, it is to be understood that these may be suitably arranged on the various sections going to make up the evaporator construction and calandria construction wherever desired. Ladders 81 and platforms 82 are also arranged for the inspection of the evaporator, and the drive for the circulator which has been described with respect to the previous embodiment.

From the above description with respect to each of the embodiments shown in Figs. 2 and 7 relating to a cast iron construction and an all-steel construction for a salt plant, it is evident that the parts have been arranged for compactness and ease in erection and dismantling in out-of-the-Way places.

In order to describe the plant in conjunction with the schematic flow diagram of Fig. 1, the operation will be described for the production of sodium chloride, or common salt, although the operation is equally satisfactory with any solid in suspension in a`solution from which it is required to separate the solid with a minimum amount of heat supplied, and a minor portion of the heat is supplied by the waste heat from the engine used in driving the auxiliary, such as the blower or compressor for compressing the hot vapors of the solution to add the major portion lof the additional heat for the evaporative process provided by the latent heat of the vapors. In connection with the operation of a salt plant, there may be used a brine solution with approximately a 16 F. boiling point rise. It has been found that boiling at atmospheric pressure is satisfactory, and that a temperature gradient of 20 F. between the heating element and the boiling brine is satisfactory. It is to be understood that this 20 F. temperature gradient is illustrative only, and that other values can be used without departing from the scope of this invention. Thus there is established one possible set of conditions with brine boiling at 212 F. plus 16 F. equals 228 F.; and the vapor in the Calandria or heater 17 of 228 F. plus a temperature gradient of 20 F. equals 248 F. This relationship provides a P1 of 14.7 pounds per square inch absolute as the pressure of the vapors in the evaporator, and a P2 of 28.8 pounds per square inch absolute as the pressures of the vapors in the heater which provides a compression ratio of 28.8 over 14.7 equals 1.96. In the preferred embodiment, there is required a compressor 19 with a compression ratio of 1.96 and a volumetric capacity equivalent to the evaporative capacity required, connected to an internal combustion engine usin'g gas or liquid fuel, such as diesel engine 21 equipped with a waste heat recovery system 27, such as the vapor phase cooling and waste heat recovery, with which about 3300 B. t. u. per brake horsepower is recoverable. This type of waste heat recovery system is readily available, and is used for recovering waste heat from the engine and engine exhaust.

When it is considered that each brake horsepower applied to compressor 19 appears as the heat of compression in the vapors from the evaporator and is recoverable, and that in a normal size plant, such as herein described, it requires about 0.42 pound of oil containing 19,000 B. t. u. per pound per brake horsepower, therefore, for each brake horsepower developed, there is available 0.42 19,000 equals 7980 B. t. u. input basis for the fuel. When this is recovered, there is realized 3300 B. t. u. plus 2547 B. t. u. per B. H. P. which equals 5847 B. t. u. The thermal eiciency on the basis of the fuel burned is then 5847x100 divided by 7980 which equals 73.25%.

The brine boiling in the evaporator at 228 F. produces the vapor which is picked up by the compressor and compressed to 28.8 p. s. i. a., corresponding to a saturated temperature o-f 248 F. when the super-heat has been removed, which is accomplished by adding, as a fog or spray, sufficient condensate through the fogging nozzle connection 64, Fig. l, which when vaporized, consumes or removes the super-heat, these vapors being dis- 12 Y charged to the heating element of the evaporator. The latent heat in the vapors being compressed, the heat of compression, and the waste heat recovered from the engine, may be more than required in the evaporation process. The heat thus furnished is more than required to evaporate the necessary amount of water. This excess heat is therefore bled away from the heating element, together with the non-condensible gases to the condensate receiving tank 23, the non-condensible gases being discharged through the air vent 63, or the excess heat is controlled by by-passing around the waste heat boiler to the atmosphere, the necessary amount of engine exhaust gases.

The thermodynamic requirements of this system may require such amounts of power input that the system cannot utilize the heat developed. `This condition would probably exist when processing solutions with a high boiling point rise. This is the basic source of excess heat. lf bleeding the non-condensibles away from the system does not take care of the excess heat, a valve controlled Iby-pass 27a around the waste heat boiler 27 to by-pass a part of the hot engine exhaust may be used.

Inasmuch as no heat is lost from the system through the use of a condenser, and as better than' 70% of the heat value of the fuel oil is utilized, it becomes evident that this method of production by evaporative means is more economical than that accomplished by standard methods. For example, a set of triple eect evaporators commonly used in producing common salt has steam requirements at the heater so that there will be produced a pound of salt per 1208 B. t. u., while a single effect pantype evaporator with a compression cycle as disclosed in connection with the embodiment of this invention will produce a pound of salt for each 637 B. t. u. as heat added to the heating element, which, therefore, is on a comparable basis.

The process as disclosed in connection with the several embodiments of this invention may utilize equally well either an internal calandria 17 or 17', or an external heater (not shown) which utilizes rapid circulation or high ilow heaters, as the circumstances may warrant, as is well understood by those skilled in the art. As evaporation continues, the salt is produced and handled in a conventional evaporator exactly as in any standard operation of the prior art. The salt which collects in the salt leg 15 is partially washed rby passing the incoming feed brine from the salt dissolver 10 up the salt leg to the main body of the evaporator. The salt is continuously discharged as a slurry by the slurry pump 35, which is preferably an adjustable speed pump operating at such a rate as to give the desired density of slurry, usually thirty to thirty-five percent salt, directly to the continuous filter or centrifugal lter 37 for dewatering. With a continuous centrifugal filter and a conventional-type drier, the salt may be taken to one-half of one percent molsture, or less, or the slurry can Ibe fed to a conventional top feed lilter where it can be dried to the same dryness.

It is obvious that the salt plant `as herein disclosed requires no other fuel for the evaporative process than that used in the engine, except possibly where it is desired to use other types of heaters to assist in the original start-up of the plant, which also may be provided by the same internal combustion engine which drives the compressor but, in addition, has a generator connected thereto for providing power for the lauxiliary heaters. Therefore, no boiler plant or condenser is required, and the plant is also capable of operating with a very vminimum of water requirements, which is essential in out-ofthe-way locations where fresh water may be unobtainable. The only fresh water required for this plant when operating on brine made by dissolving solar or rock salt is that due to leakage and minor evaporation losses, thus making this plant ideal for locations where fresh water is not readily available.

With .a salt plant having the evaporator as described, salt crystals may be retained in the circulating brine, or other liquid, and built up to any desired size within reasonable limits. The crystals, which are of such size as would have a tendency to drop out of the brine or liquid when coming down through the Well or central aperture 77, separate from the brine and drop to the bottom of the evaporator, and will tend to fall into the salt leg 15, where they are pumped out as slurry. As the brine, or other liquids, circulate toward the bottom of the Calandria, shaped as illustrated in Fig. 4, and up through the calandria tubes, the brine, or other liquid, carries the crystals therewith, thus keeping them circulating with the brine. However, after the crystals have reached an appreciable size, they will have a tendency to drag along the bottom of the trough, as illustrated in Fig. 4, below the circulator 75, and will finally drop over into the salt leg. The size of the crystals may be controlled, as is well understood in the art, such as by using in the calandria a salt pan such as disclosed and claimed in the aforementioned patents.

lt is obvious that there has been disclosed a very eti-lcient form of evaporator, such as a Salt plant, which is very eicient to operate, and may be erected in far away locations where fresh water is more or less unobtainable.

It is also obvious that there has been provided a simple system for boiling out the evaporator after periods of operation to reduce the scaling, and to increase the e'- ciency of operation.

There has also been disclosed, where fresh water is unobtainable, a simple form of auxiliary evaporator to produce make-up water from contaminated water, and where it is an advantage to further conserve heat losses, a heat exchanger may be used in connection with the auxiliary evaporator for producing make-up water.

There has also been disclosed a simple system in which the brine heater by-pass for the hot condensate may be controlled by the vapor temperature within the evaporator, and there has been provided a simple control system wherein the boil-out water temperature in the tank therefor may be used to control the by-pass for the hot condensate, which is used to heat the fresh water to the boil-out water tank.

There has also been disclosed a simple system for heating the brine within the evaporator by using the waste heat of the engine and the exhaust gases thereof by circulating cooling water through the engine, and a waste heat boiler for the exhaust gases to which is added the heat conserved by compressing the hot vapors from the evaporator, the heat of the compressed hot vapors being Idischarged into the Calandria.

Although the invention has been particularly disclosed for a one-ton-per-hour unit salt plant, it is within the scope of the invention that larger capacity plants may be built following the principles of this invention without departing from the scope thereof, and also that the invention is equally adaptable for producing solids or crystalline materials from solutions, or from other forms of naturally occurring brincs. Likewise, it may be used for recovery of liquors, etc., from the waste liquors of various cellulosic processes, to prevent the contamination of streams into which the waste liquors usually are dumped. It may also be used for the production of sugar crystals in the rening of either cane or beet sugars, or from the sap of maple trees, and for the producing of any solids, which can be recovered by evaporation.

Furthermore, although the invention has been described in conjunction with a single evaporator, the invention is equally adapted for use with more than one evaporator suitably connected in parallel, and the system modified accordingly within the scope of the invention,

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence, I do not wish to be understood as limiting myself to the exact form, construction, arrangement, and combination of parts herein shown and described, or uses mentioned.

What I claim as new and desire to secure by Letters lPatent is:

l. T-he method of producing solids from .a solution including solids in suspension by evaporation Within an evaporator including a heating element and provided with a vapor space, which comprises the steps: boiling a solution of the solids to be separated, thus causing the vapors of the solution to be liberated, compressing t-he vapors within a predetermined range of compression ratio, thereby raising the temperature of the vapors from within the vapor space of the evaporator by compression means operatively driven by a heat engine and thereby causing the liberated vapors to be superheated within a predetermined temperature range, said engine including a Waste heat recovery system in heat exchange relationship with the heating element of the evaporator in order for the heat engine to be cooled, discharging the superheated and compressed vapors to the heating element of the evaporator, thus causing the superheated and compressed vapors to be condensed by giving up their latent heat to the boiling solution in heat exchange relationship with said heating element, bleeding away from the heating element of the evaporator the non-condensible gases and any excess heat, thereby causing the solids to be separated from the solution with the solids in suspension, and reducing the temperature of the superheated vapors during compression by spraying la condensate from the heating side of the heating element of the evaporator into the suction side of the compression means which in vaporizing continuously removes the heat of compression throughout the compression cycle so as to produce a compressed vapor at substantially its saturated temperature.

- 2. The method of producing solids from a solution including solids in suspension by evaporation within an evaporator including a heating element. and provided with a vapor space, which comprises the steps: boiling a solution of the solids to be separated, 4thus causing the vapors of the solution to be liberated, compressing the vapors within a predetermined Vrange of compression ratio, thereby raising the temperature of the vapors from Within the vapor space of the evaporator by compression means operatively driven by a heat engine and thereby causing the liberated vapors to be superheated within a predetermined temperature range, said engine including a waste heat recovery system in heat exchange relationship with 4the heating element of the evaporator in order for the heat engine to be cooled, discharging the superheated and compressed vapors to the heating element of the evaporator, thus causing the superheated and compressed vapors to be condensed giving up their latent heat 'to the boiling solution in heat exchange relationship with said heating element, bleeding away from the heating element of the evaporator the non-condensible gases and any excess heat, thereby causing the solids to be separated from the solution within the solids in suspension, evaporating contaminated water from a source thereof within an auxiliary evaporator to produce pure make-up water by utilizing a portion of `the hot compressed vapors resulting from the vapor compression in heat exchange relationship with said contaminated water within the auxiliary evaporator, vaporizing said contaminated water, and condensing the liberated vapors of the contaminated water.

3. The method of producing salt from a natur-ally occurring brine by evaporation within an evaporator including a heating element and provided with a vapor space, which comprises the steps: boiling a solution of the solids to be separated, raising the temperature of the liberated vapors from within the vapor space of the evaporator by compressing the liberated vapors within a predetermined range of compression ratio by compression means operatively driven by a heat engine and there'- by causing the liberated vapors to be superheated within a predetermined temperature range, said heat engine including an exhaust system and a waste heat recovery system in heat exchange relationship withsaid exhaust system and the heating element of the evaporator, said heat engine and its exhaust being cooled by being in heat exchange relationship with a continuously owing cooling fluid through said heat engine and waste heat recovery system thereby removing the surplus heat and causing the engine and its exhaust to be cooled by discharging the continuously owing heated cooling fluid to the heating element of the evaporator, reducing the temperature of the superheated vapors within the compression means by spraying condensate from the evaporator which on vaporizing reduces the superheat of the liberated vapors, discharging the compressed liberated vapors at substantially the saturation temperature thereof to the heating element of the evaporator, Where by heat exchange relationship the compressed liberated vapors are condensed giving up their latent heat and the cooling fluid giving up any `available sensible heat to the continuously circulated solution within the heating element, causing the solution to boil, thereby liberating solution vapors, and the engine and the engine exhaust to be cooled, and bleeding the non-condensible gases and excess heat away from the heating element causing the solution to concentrate and salt to crystallize out of the naturally occurring brine, while continuously removing the produced condensate and engine cooling fluid from the heating element of the evaporator to a condensate receiving tank.

4. The method of recrystallization of a salt from a solution made by dissolving a crude and impure salt by evaporation of said solution within an evaporator including a heating element and provided with a vapo-r space, which comprises the steps: boiling a solution of the solids to be separated and thereby causing liberated vapors thereof to be formed, compressing the liberated vapors within a predetermined range of compression ratio and thereby raising the temperature of the liberated vapors from within the evaporator, by compression means operatively driven by a heat engine and thereby causing the liberated vapors to be superheated within a predetermined temperature range, said heat engine including an exhaust system and a waste heat recovery system in heat exchange relationship with said exhaust sysi tern and the heating element of the evaporator7 discharging these compressed vapors and the engine cooling water from the waste heat recovery system to the heating element of the evaporator so that the latent heat of the compressed vapors and sensible heat of the engine coolf ing water are given up to the boiling Solution in heat exchange relationship thus causing the solution to concentrate and the salts to crystallize therefrom, and producing make-up water required for the method of recrystallization from any contaminated water available by using in part the surplus heat from the system.

5, In the method as set forth in claim 4, the step of providing pure make-up water by contacting a contaminated water within an auxiliary evaporator including a heat exchange means with a portion of the hot compressed vapors from the compression means, condensing said ho-t compression vapors by boiling said contaminated water, thereby producing pure make-up water while the vapors from the boiling contaminated water are returned to the compression means.

6. The method in an evaporative process of recrystallization of salts from a solution thereof by evaporation within an evaporator provided with a vapor space and including a salt leg, an internal calandria including a heat exchanger', a vapor compressor operatively driven by an internal combustion engine including a waste heat boiler and a cooling fluid for circulation through said engine, waste heat boiler and heat exchanger of said internal calandria, which comprises the steps: dissolving a salt within a salt dissolver in condensate produced by the liti evaporative process, thus forming a solution of the salt to be separated, passing the solution through a second heat exchanger causing the temperature thereof to be raised to a predetermined temperature by recovering the heat from the condensate from the evaporator, said condensate being that formed by condensing the compressed vapors, discharging the heated solution to the evaporator, continuously circulating the solution within the Calandria of the evaporator, thereby causing the solution to be brought to boiling temperature, whereby vapor is liberated and solids separated and in suspension as a slurry within the salt leg, compressing the liberated vapors from the boiling solution from the vapor space of the evaporator by the vapor compressor driven by the internal combustion engine operatively connected to the waste heat recovery system, discharging the compressed vapors to the heat exchanger of the Calandria of the evaporator, thereby causing the vapors to be condensed by the removal of the latent heat in heat exchange relationship with the boiling solution, returning the condensate so formed to the salt dissolver, withdrawing the salt slurry from the salt leg of the evaporator, filtering the salt from the solution, drying the salt and returning the filtered solution to either the salt dissolver or the evaporator as the evaporative process of recrystallization of salts may require.

7. In the method as set forth in claim 6, the step of recycling the said cooling fluid fo-r the engine continuously at a uniform rate through the engine and said heat exchanger of said internal Calandria.

8. In the method as set forth in claim 6, the step of recycling the cooling fluid continuously at a uniform rate through the waster heat boiler operatively connected in heat exchange relationship to the exhaust of the heat engine.

9. In the method as set forth in claim 6, the steps of collecting the hot condensate from the Calandria within a condensate-receiving tank, discharging the hot condensate through a fresh water heater and a brine heater causing fresh water for boil-out water to be heated and brine for the evaporator to be heated, and controlling the rate of discharge of the condensate through the fresh water heater and brine heater to the salt dissolver by the height of the condensate within the condensate-receiving tank, while condensate for engine cooling water and for the waste heat boiler is continuously recycled through the condensate-receiving tank.

l0. ln the method as set forth in claim 6, the step of accumulating salt within the salt leg of the evaporator.

1l. In the method as set forth in claim 6, the step of maintaining a constant level of the brine within the evaporator by controlling the amount of brine circulated to the evaporator from the salt dissolver in response to the height of the brine within the evaporator.

12. In the method as set forth in claim 6, the steps of collecting the hot condensate from the Calandria within a condensate-receiving tank discharging some of the hot condensate through a fresh water beater thus causing fresh water for boil-out water to be heated through the aforesaid second heat exchanger and thus causing the brine for the evaporator to be heated, and controlling the discharge rate of the condensate through the fresh water heater and the second heat exchanger to the salt dissolver by the height of the condensate within the condensate-receiving tank.

13. In the method as set forth in claim 6, the steps of collecting the hot condensate from the Calandria within a condensate-receiving tank, discharging the hot condensate through a fresh water heater thereby causing fresh water for boil-out water to be heated in heat exchange relationship with the hot condensate, and controlling the discharge of the condensate through the fresh water heater to the salt dissolver by the height of the condensate within the condensate-receiving tank, raising the temperature of the feed brine from the salt dissolver substantially within the range of the available temperature of the hot condensate by heat exchange relationship therewith in the second heat exchanger and discharging the feed brine directly to the evaporator.

14. In the method as set forth in claim 6, the step of collecting the condensate from the Calandria within a condensate-receiving tank for discharge through a fresh water heater, a brine heater and to the salt dissolver by controlling the level of the condensate within the Condensate-receiving tank.

15. In the method as set forth in claim 14, the step of recycling the cooling fluid also through the condensatevreceiving tank continuously at a uniform rate.

1,6. In the method as set forth in claim 6, the steps of continuously accumulating fresh water for boil-out water, and heating slowly and continuously the fresh water with the hot condensate between the boil-out periods, said hot condensate being the aforesaid condensate produced by condensing the compressed vapors.

17. In the method as set forth in claim 16, the steps of discharging brine from the salt dissolver to the evaporator, and simultaneously discharging the aforesaid produced hot condensate from a condensate-receiving tank in heat exchange relationship with respect to fresh water and the brine.

18. ln the method as set forth in claim 16, the step of circulating boil-out water through the evaporator to remove lumps of salt and scale formed therein, after stopping the compressing of vapors from the evaporator, and withdrawing the brine from the evaporator to a pump-back tank.

19. In the method as set forth in claim 18, Vthe steps of returning the brine from the pump-back tank to the evaporator after stopping the circulation of boil-out water, and reinitiating the compression and recycling of vapors from the evaporator. t

20. In the method as set forth in claim 19, the step of recirculating the brine within the Calandria causing the salt to separate out into crystals of a predetermined size.

21. The method in an evaporative process of recrystallization of salts from a solution thereof by evaporation within an evaporator provided with a vapor space and comprising an internal Calandria including a heat exchanger, operatively connected to a heat engine including a waste heat recovery system, said engine driving a vapor compressor, which comprises the steps: dissolving salt within a salt dissolver in condensate produced by the evaporative process thus forming a solution of salt to be recrystallized, circulating the solution through a second heat exchanger thereby causing the temperature thereof to be raised to a predetermined temperature by heat exchange relationship with the hot condensate from the calandria of the evaporator, discharging the heated solution to the evaporator, circulating the solution continuously through the calandria of the evaporator, where in heat exchange relationship, the solution'is brought to the boiling temperature by a iiuid circulated through the engine and the waste heat boiler connected in heat exchange relationship to the engine exhaust, compressing the vapors from the boiling solution from within the vapor space of the evaporator by a compressor driven by a heat engine, discharging the compressed solution vapors within the Calandria of the evaporator where in heat exchange relationship with the boiling solution, the compressed vapors give up their latent heat to the boiling solution, thus causing the compressed vapors to condense and the boiling solution to concentrate by vaporization, and further causing salt to crystallize from the solution and suspend therein forming a slurry, withdrawing the slurry from the evaporator, filtering the salt from the solution, drying the salt, returning the filtered solution to the salt dissolver, and providing pure makeup water required for the method of recrystallization from any available contaminated water by recirculating a portion of the compressed and heated solution vapors as discharged by the compressor to an auxiliary evaporator, where in heat exchang relationship Within the auxiliary evaporator, the said compressed vapors are caused to condense by giving up their latent heat to the boiling contaminated water, and discharging the condensate so produced as pure make-up water to the salt dissolver.

22. The method of providing pure make-up water from any available raw water for use in a salt plant including an evaporator producing vapors from a boiling solution, and a compressor for compressing the vapors, which comprises the steps: discharging a portion of the compressedV vapors from the compressor to a heating element of an auxiliary evaporator being fed with raw water, condensing this portion of the vapors by removing the latent heat by heat exchange relationship with the boiling raw water, thereby producing condensate which is the pure make-up water, discharging the vapors from the boiling raw Water from the vapor space of the auxiliary evaporator to the suction side of the compressor, and recovering the heat from the produced condensate and from the concentrated raw Water blowdown from the auxiliary evaporator by heat exchange relationship with the raw Water being fed to the auxiliary evaporator thereby heating the raw water feed.`

23. A salt plant comprising in combination, an evaporator for producing salt crystals from a salt solution, including a Calandria and a leg pipe, :a compressor operatively connected to the evaporator, an engine including a cooling system and operativelyconnected to the compressor for driving the compressor,I a waste heat boiler in heat exchange relationship with the engine exhaust, engine coo-ling fluid for circulating through the cooling system and the waste heat boiler, a condensate receiving tank operatively connected to the calandria and to the Cooling-system of-the engineand the waste heat boiler, condensate from the condensate receiving tank being Continuously circulated through the engine cooling system and the waste heat boiler as the engine cooling uid removes the waste heat from the engine and the exhaust by heat exchange relationship, discharging the hot engine cooling fluid to the calandria, raising the temperature of the solution within the calandria by heat exchange relationship with the circulatnig hot engine cooling Huid, recovering the Waste heat therefrom by vaporizing the solution, and said compressor being adapted for compressing the solution vapors within the Compressor and discharging the compressed vapors to the calandria to extract the latent heat thereof, whereby the solution is caused to evaporate by the heat recovered from the engine cooling uid and the heat obtained from the compressed vapors thus assuring suicient heat to sustain the salt plant in continuous independent operation, and spray means for reducing the superheat as rapidly as it becomes available in the solution vapors during the compression, by spraying a portion of the condensate from the calandria into the solution vapors prior to compressing the solution vapors, whereby the compressed vapors are discharged from the cornpressor at substantially saturation temperature, thereby decreasing the power necessary for compression.

24. A salt plant comprising in combination, an upright evaporator for a salt solution being evaporated and positioned upon a calandria comprising a heat exchanger including a steam belt and a circulator for heating the solution and a salt leg operatively connected to the evaporator, a compressor including an inlet and an outlet and adapted for compression of the solution vapors from the vapor space of the evaporator, said inlet of the Compressor being operatively connected to receive vapors from the vapor space of the evaporator, said compressor after compressing the vapors, being adapted to discharge the compressed vapors to the steam belt of the calandria, an internal combustion `engine for loperatively driving the compressor and including a cooling system and a waste heat boiler in heat exchange relationship with the engine exhaust, whereby as said vapors from the heated solution are compressed with a resultant'increase in temperature and discharged into the steam belt of the Calandria, the engine cooling water is circulated through the engine and the Waste heat boiler and discharged to the Calandria, means for driving the circulator for continuously circulating the solution within the Calandria in heat exchange relationship with the heated engine cooling water and the cornpressed vapors from the boiling solution, a fogging nozzle adapted for discharging condensate from the calandria into the vapors from the evaporator prior to the compression thereof in the compressor to reduce the superheat of the vapors and prevent crystals forming within the compressor and to decrease power required for compression, and said vapors being discharged from the compressor at substantially the saturation temperature.

25. The combination with an evaporator including a Calandria having a heat exchanger and a circulator for the solution to be evaporated, of a condensate receiver adapted to receive condensate from the heat exchanger of the evaporator, a brine heater operatively connected to the condensate receiver for heating the brine discharged to the Calandria, means for providing make-up water to replace any lost from the system, and a fresh Water heater operatively connected to the condensate receiver, whereby the hot condensate is adapted to preheat the brine and fresh water solution, and said brine heater and fresh water heater operatively mounted contiguous to the condensate receiver.

26. The combination with an evaporator including a Calandria and a heat exchanger therefor, of means for heating a solution including solids to be separated, said means including an internal combustion engine and a compressor driven thereby for compressing vapors from the evaporator operatively connected with the engine to recover the Waste heat therefrom, a solids dissolving tank, a condensate tank, and a heat exchangerkoperatively connected together and to the evaporatorin heat exchange relationship with the hot condensate from the condensate tank for heating the solution to be evaporated, a boil-out water tank and a pump-back tank, said solution from the evaporator adapted to be discharged to the pump-back tank, pump means being adapted for circulating boil-out water through the evaporator for cleaning the evaporator, and a heat exchanger operatively connected to the boil-out Water tank and adapted for heating fresh water to provide the boil-out water as it is continuously admitted to the boil-out Water tank, and said pump means being adapted to return the solution from the pump-back tank to the evaporator, and said boil-out water being adapted to be discharged to the solids dissolving tank.

References Cited in the file of this patent UNITED STATES PATENTS 1,091,721 Weil Mar. 31, 1914 1,118,041 Nobel et al. Nov. 24, 1914 1,213,596 De Baufre Jan. 23, 1917 1,346,624 Wood July 13, 1920 1,558,957 White Oct. 27, 1925 1,860,118 Ray et al. May 24, 1932 1,927,555 Oetken Sept. 19, 1933 2,092,470 Peebles Sept. 7, 1937 2,185,595 Kleinschmidt Ian. 2, 1940 2,355,397 Scharnberg Aug. 8, 1944 2,396,664 Ladd Mar. 19, 1946 2,537,259 Cleaver et al. Jan. 9, 1951 2,555,340 Hopper et al. June 5, 1951 2,589,406 Latham Mar. 18, 1952 2,637,684 Buifum May 5, 1953 

